How to find the area of a parallel plate capacitor


Asked by admin @ in Physics viewed by 269 People


A parallel-plate capacitor has plates of area A. The plates are initially separated by a distance d, but this distance can be varied. The capacitor is connected to a battery.

a) What should the plate separation be if you want to halve the capacitance.
b)What should the plate separation be if you want to halve the capacitance.
c)What should the plate separation be if you want to halve the charge stored?
d) What should the plate separation be if you want to halve the charge stored?
e)What should the plate separation be if you want to halve the energy stored?
f)What should the plate separation be if you want to halve the energy stored?
g)What should the plate separation be if you want to halve the energy density?

Answered by admin @



Answer:

a) In a parallel plate capacitor the capacitance is

C = \frac{Q}{V} = \epsilon_0\frac{A}{d}

So, in order to halve the capacitance the plate separation should be twice the original distance.

b) Same question as (a).

c) According to the above equations, the charge stored in a capacitor is directly proportional to the plate separation.

\frac{Q}{V} = \frac{A}{d}

In order to halve the charge stored the plate separation should be half the original distance.

d) Same question as (c).

e) The energy stored in a capacitor is

U = \frac{1}{2}CV^2 = \frac{1}{2}\epsilon_0\frac{A}{d}(Ed)^2 = \frac{1}{2}\epsilon_0AE^2d

In order to halve the energy stored in the capacitor, the plate separation should be twice the original distance.

f) Same question as (e).

g) The energy density is given by the following equation

u = \frac{\frac{1}{2}CV^2}{Ad} = \frac{\frac{1}{2}\epsilon_0\frac{A}{d}(E^2d^2)}{Ad} = \frac{1}{2}\epsilon_0E^2.

As it turns out, the energy density is independent from the geometric factors. This makes sense, because the electric field in a parallel field capacitor is independent from the distance.


Similar Questions

A parallel-plate capacitor is charged by a 20.0 v battery, then the battery is removed.

Asked by maham237 @ in Physics viewed by 428 persons

A parallel-plate capacitor is charged by a 9.00 V battery, then the battery is removed. Part A What is the potential difference between the plates after the battery is disconnected? …

Find the area of trapezium whose parallel sides are

Asked by admin @ in Math viewed by 308 persons

Find the area of a trapezium whose parallel sides 25 cm 13cm and other sides are 15 cm 15 cm

Two parallel plate capacitors of capacitance c and 2c

Asked by admin @ in Physics viewed by 356 persons

two parallel plate capacitors of capacitance c and 2c are connected in parallel and charged to a potential difference v . if the battery is disconnected and the space between …

A parallel plate air capacitor has a capacitance c

Asked by admin @ in Physics viewed by 334 persons

14. A parallel plate air capacitor has capacitance C. Now half of the space is filled with a dielectricmaterial with dielectric constant K = 5 as shownin figure. …

A parallel plate capacitor with air between the plates

Asked by admin @ in Physics viewed by 293 persons

Question 2.5: A parallel plate capacitor with air between the plates has a capacitance of 8 pF (1pF = 10 −12 F). What will be the capacitance if the distance …

A parallel plate capacitor c has a charge q

Asked by admin @ in Physics viewed by 311 persons

A parallel plate capacitor Has a charge Q.The actual charges on the plates are (a) Q R (b) Q/2 Q/2 (c) Q -Q (d) (Q)/(2) (-Q)/(2)

The capacity of a parallel plate capacitor depends on

Asked by admin @ in Physics viewed by 310 persons

On what factors does the capacitance of a parallel plate capacitor depend

A parallel plate capacitor is charged by a battery

Asked by admin @ in Physics viewed by 299 persons

A parallel plate capacitor is charged by a battery. After some time the battery is disconnected and a dielectric slab with its thickness equal to the plate separation is inserted …

Force between two plates parallel plate capacitor

Asked by maham237 @ in Physics viewed by 296 persons

A parallel-plate capacitor is constructed of two horizontal 15.6-cm-diameter circular plates. A 1.1 g plastic bead with a charge of -6.4 nC is suspended between the two plates by the …

Derive expression for capacitance of a parallel plate capacitor

Asked by admin @ in Physics viewed by 345 persons

What is a parallel plate capacitor. Derive an expression for its capacitance?

A parallel plate capacitor consists of two circular plates

Asked by admin @ in Physics viewed by 317 persons

A parallel plate capacitor consists of two circular plates each of radius 2 cm, separated by a distance of 0.1 mm. If voltage across the plates is varying at the …

A parallel plate capacitor is charged and then isolated

Asked by admin @ in Physics viewed by 370 persons

A parallel plate capacitor is charged and then isolated. What is the effect of increasing the plate separation on charge, potential, capacitance, respectively? (a) constant, decreases, decreases (b) increases, decreases, …

How to find the surface area of a regular pyramid

Asked by admin @ in Mathematics viewed by 306 persons

Find the surface area of the regular pyramid. 10 yd 9 yd 7.8 yd lyd?

How to find area of z score on ti 84

Asked by admin @ in Mathematics viewed by 292 persons

Find the -scores that bound the middle 96 of the area under the standard normal curve by using the TI-84 calculator.

How do you find the area of a rectangular prism

Asked by admin @ in Mathematics viewed by 289 persons

could you use the formula for the surface area of a rectangular prism to find the surface area of a cube explain please help me.

Most viewed questions in Physics


Jeevandeep health and physical education std 10 answers pdf

Asked by admin @ in Physics viewed by 11059 persons


Hc verma physics class 9 solutions of describing motion

Asked by admin @ in Physics viewed by 2661 persons


How to leave nightmare land answer key

Asked by maham237 @ in Physics viewed by 1587 persons



Base area and stability of some objects with different shapes

Asked by admin @ in Physics viewed by 1522 persons


Which of the following statements about safe lifting are correct

Asked by admin @ in Physics viewed by 1508 persons


Porous water-absorbing mass of fibers

Asked by wiki @ in Physics viewed by 1487 persons



Absorption of water by filter paper is due to

Asked by admin @ in Physics viewed by 1426 persons


A composite wire of uniform diameter 3mm

Asked by admin @ in Physics viewed by 1397 persons


At a distance l 400m from the traffic light

Asked by admin @ in Physics viewed by 1313 persons



A rocket of mass m is launched straight up with thrust f⃗ thrust.

Asked by maham237 @ in Physics viewed by 1309 persons


Mind map for light reflection and refraction class 10

Asked by admin @ in Physics viewed by 1137 persons



A thief runs at a speed of 10m s

Asked by admin @ in Physics viewed by 1091 persons


A 5.8 x 10 4 watt elevator motor can lift

Asked by maham237 @ in Physics viewed by 1076 persons